Improved Jupyterlab Support

This release includes a several new features including better integration with jupyterlab plotting, better documentation, and a variety of fixes.

The following is a non-comprehensive list of changes, features, and bug-fixes:

New Features

• Add shadows
• Add physically based rendering
• Add jupyter backends

Documentation

• Interactive examples on docs.pyvista.org
• Use pydata-sphinx-theme
• Improve pyvista.Camera class documentation.

API Changes

• Refactor inplace so it always returns an object.

Bug Fixes

• Fix Window Closing
• Fix docstrings
• Fix floor coloring